A multicast or broadcast transmission conveys information to a group of wireless devices efficiently in terms of the radio resources used. Moreover, such a transmission may reduce the amount of time needed to deliver the information to the group of devices, as compared to for example multiple unicast transmissions. A multicast or broadcast transmission may be realized using transmission schemes such as Multimedia Broadcast Multicast Services (MBMS) Single-Frequency Network (SFN) transmission or Single-Cell Point-to-Multipoint (SC-PTM) transmission.
Challenges faced in performing multicast or broadcast include informing wireless devices about control information for the multicast or broadcast service. In SC-PTM, part of the control information is sent over Single-Cell Multicast Control Channel (SC-MCCH) logical channel. 3GPP TS 36.321. Devices interested in receiving multicast/broadcast service are not expected to monitor this channel continuously, but an indication of change to this information is indicated on a continuously monitored physical downlink control channel (PDCCH) addressed by a special radio network temporary identifier; namely, SC-N-RNTI. 3GPP TS 36.213; 36.302; 36.331. Likewise for Multimedia Broadcast Multicast Service (MBMS) SFN (MBSFN), part of the control information is sent over Multicast Control Channel (MCCH). Changes are indicated on PDCCH addressed by M-RNTI in this case.
Continuous monitoring of a control channel such as PDCCH consumes scarce power resources, especially for devices such as Machine-Type Communication (MTC), narrowband internet of things (NB-IoT) devices, and the like. Monitoring SC-N-RNTI or M-RNTI for SC-MCCH or MCCH change, therefore, proves problematic in that it increases device power consumption and radio resource usage. Further, there are concerns with how to provide various update indications to wireless devices that are not monitoring a particular channel.